Some time ago I had to commission an asynchronous motor driving a fan (directly connected without a belt).
The motor seemed rather small for the application as the current was somewhat higher then the nominal current at 50 Hz
(4KW, Inom = 9.5A, actual current = 9.7 A). I started with a cold motor, and after a while the current decreased slowly
to about 9.5 A. I must say the motor had long motor cabled (120m) and no output choke.
Could an increase of the resistance of the motor windings due to temperature be the reason for the lower current?
At the time of the test the drive was in U/F control.
What if I should put the drive in sensorless vector control?
Would the drive then sense the higher motor temperature through current calculation and compensate for the higher estimated resitance, and would this result in a current independant of the motor temperature?
The motor seemed rather small for the application as the current was somewhat higher then the nominal current at 50 Hz
(4KW, Inom = 9.5A, actual current = 9.7 A). I started with a cold motor, and after a while the current decreased slowly
to about 9.5 A. I must say the motor had long motor cabled (120m) and no output choke.
Could an increase of the resistance of the motor windings due to temperature be the reason for the lower current?
At the time of the test the drive was in U/F control.
What if I should put the drive in sensorless vector control?
Would the drive then sense the higher motor temperature through current calculation and compensate for the higher estimated resitance, and would this result in a current independant of the motor temperature?